Method of polishing a multi-layer substrate

ABSTRACT

The invention provides a system for polishing one or more layers of a multi-layer substrate that includes a first metal layer and a second layer comprising (i) a liquid carrier, (ii) at least one oxidizing agent, (iii) at least one polishing additive that increases the rate at which the system polishes at least one layer of the substrate, wherein the polishing additive is selected from the group consisting of pyrophosphates, condensed phosphates, phosphonic acids and salts thereof, amines, amino alcohols, amides, imines, imino acids, nitrites, nitros, thiols, thioesters, thioethers, carbothiolic acids, carbothionic acids, thiocarboxylic acids, thiosalicylic acids, and mixtures thereof, and (iv) a polishing pad and/or an abrasive. The invention also provides a method of polishing a substrate comprising contacting a surface of a substrate with the system and polishing at least a portion of the substrate therewith. Moreover, the invention provides a method for polishing one or more layers of a multi-layer substrate that includes a first metal layer and a second layer comprising (a) contacting the first metal layer with the system, and (b) polishing the first metal layer with the system until at least a portion of the first metal layer is removed from the substrate.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This patent application is a divisional of copending U.S. patentapplication Ser. No. 09/636,161, filed Aug. 10, 2000, which claims thebenefit of U.S. Provisional Patent Application No. 60/148,813, filedAug. 13, 1999.

TECHNICAL FIELD OF THE INVENTION

[0002] This invention pertains to a polishing system and a method ofpolishing a substrate, particularly a multi-layer substrate thatincludes a first metal layer and a second layer.

BACKGROUND OF THE INVENTION

[0003] Integrated circuits are made up of millions of active devicesformed in or on a substrate, such as a silicon wafer. The active devicesare chemically and physically connected into a substrate and areinterconnected through the use of multilevel interconnects to formfunctional circuits. Typical multilevel interconnects comprise a firstmetal layer, an interlevel dielectric layer, and sometimes a third andsubsequent metal layer. Interlevel dielectrics, such as doped andundoped silicon dioxide (SiO₂) and/or low-κ dielectrics, are used toelectrically isolate the different metal layers.

[0004] The electrical connections between different interconnectionlevels are made through the use of metal vias. U.S. Pat. No. 5,741,626,for example, describes a method for preparing dielectric TaN layers.Moreover, U.S. Pat. No. 4,789,648 describes a method for preparingmultiple metallized layers and metallized vias in insulator films. In asimilar manner, metal contacts are used to form electrical connectionsbetween interconnection levels and devices formed in a well. The metalvias and contacts may be filled with various metals and alloys, such as,for example, titanium (Ti), titanium nitride (TiN), aluminum copper(Al—Cu), aluminum silicon (Al—Si), copper (Cu), tungsten (W), andcombinations thereof (hereinafter referred to as “via metals”).

[0005] The via metals generally employ an adhesion layer (i.e., abarrier film), such as a titanium (Ti), titanium nitride (TiN), tantalum(Ta), tantalum nitride (TaN), tungsten (W), or tungsten nitride (WN)barrier film, to adhere the via metals to the SiO₂ substrate. At thecontact level, the barrier film acts as a diffusion barrier to preventthe via metals from reacting with SiO₂.

[0006] In one semiconductor manufacturing process, metal vias and/orcontacts are formed by a blanket metal deposition followed by achemical-mechanical polishing (CMP) step. In a typical process, viaholes are etched through an interlevel dielectric (ILD) tointerconnection lines or to a semiconductor substrate. Next, a barrierfilm is formed over the ILD and is directed into the etched via hole.Then, a via metal is blanket-deposited over the barrier film and intothe via hole. Deposition is continued until the via hole is filled withthe blanket-deposited metal. Finally, the excess metal is removed bychemical-mechanical polishing (CMP) to form metal vias. Processes formanufacturing and/or CMP of vias are disclosed in U.S. Pat. Nos.4,671,851, 4,910,155, and 4,944,836.

[0007] Typical metal CMP systems contain an abrasive material, such assilica or alumina, suspended in an oxidizing, aqueous medium. U.S. Pat.No. 5,244,534, for example, discloses a system containing alumina,hydrogen peroxide, and either potassium or ammonium hydroxide, which isuseful in removing tungsten with little removal of the underlyinginsulating layer. U.S. Pat. No. 5,209,816 discloses a system useful forpolishing aluminum that comprises perchloric acid, hydrogen peroxide,and a solid abrasive material in an aqueous medium. U.S. Pat. No.5,340,370 discloses a tungsten polishing system comprising potassiumferricyanide, potassium acetate, acetic acid, and silica. U.S. Pat. No.5,391,258 and U.S. Pat. No. 5,476,606 disclose systems for polishing acomposite of metal and silica which includes an aqueous medium, abrasiveparticles and an anion which controls the rate of silica removal. U.S.Pat. No. 5,770,095 discloses polishing systems comprising an oxidizingagent, a chemical agent, and an etching agent selected from aminoaceticacid and amidosulfuric acid. Other polishing systems for use in CMPapplications are described in U.S. Pat. Nos. 4,956,313, 5,137,544,5,157,876, 5,354,490, and 5,527,423.

[0008] Barrier films of titanium, titanium nitride, and like metals,such as tungsten, are chemically active in general. Thus, such barrierfilms are similar in chemical nature to via metals. Consequently, asingle system can be used effectively to polish both Ti/TiN barrierfilms and via metals at similar rates. Ta and TaN barrier films,however, are significantly different from Ti, TiN, and like barrierfilms. Ta and TaN are relatively inert in chemical nature as compared toTi and TiN. Accordingly, the aforementioned systems are significantlyless effective at polishing tantalum layers than they are at polishingtitanium layers (e.g., the tantalum removal rate is significantly lowerthan the titanium removal rate). While via metals and barrier metals areconventionally polished with a single system due to their similarly highremoval rates, joint polishing of via metals and tantalum and similarmaterials using conventional polishing systems results in undesirableeffects, such as oxide erosion and via metal dishing.

[0009] Consequently, there remains a need for a system and/or method ofpolishing a substrate comprising a first metal layer and a second layerin a manner such that planarization efficiency, uniformity, and removalrate are maximized and undesirable effects, such as surfaceimperfections and damage to underlying topography, are minimized. Theinvention provides such a system and method. These and othercharacteristics and advantages of the present invention will be apparentfrom the description of the invention provided herein.

BRIEF SUMMARY OF THE INVENTION

[0010] The present invention provides a system for polishing one or morelayers of a multi-layer substrate that includes a first metal layer anda second layer comprising (i) a liquid carrier, (ii) at least oneoxidizing agent, (iii) at least one polishing additive that increasesthe rate at which the system polishes at least one layer of thesubstrate, wherein the polishing additive is selected from the groupconsisting of pyrophosphates, condensed phosphates, phosphonic acids andsalts thereof, amines, amino alcohols, amides, imines, imino acids,nitrites, nitros, thiols, thioesters, thioethers, carbothiolic acids,carbothionic acids, thiocarboxylic acids, thiosalicylic acids, andmixtures thereof, and (iv) a polishing pad and/or an abrasive.

[0011] The present invention also provides a method of polishing asubstrate comprising contacting a surface of a substrate with theaforementioned system and polishing at least a portion of the substratetherewith. Moreover, the present invention provides a method forpolishing one or more layers of a multi-layer substrate that includes afirst metal layer and a second layer comprising (a) contacting the firstmetal layer with the system, and (b) polishing the first metal layerwith the system until at least a portion of the first metal layer isremoved from the substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention provides a system and method for polishingone or more layers of a multi-layer substrate that includes a firstmetal layer and a second layer. The system for polishing one or morelayers of a multi-layer substrate that includes a first metal layer anda second layer comprising (i) a liquid carrier, (ii) at least oneoxidizing agent, (iii) at least one polishing additive that increasesthe rate at which the system polishes at least one layer of thesubstrate, wherein the polishing additive is selected from the groupconsisting of pyrophosphates, condensed phosphates, phosphonic acids andsalts thereof, amines, amino alcohols, amides, imines, imino acids,nitrites, nitros, thiols, thioesters, thioethers, carbothiolic acids,carbothionic acids, thiocarboxylic acids, thiosalicylic acids, andmixtures thereof, and (iv) a polishing pad and/or an abrasive.Components (i), (ii), and (iii) of the system of the present inventionare collectively referred to hereinafter as “the liquid portion of thesystem.” The abrasive forms part of the liquid portion of the systemwhen present and suspended in the liquid carrier.

[0013] The system of the present invention can be used to polish anysuitable substrate, especially one or more layers of a multi-layersubstrate. Preferably, the system of the present invention is used topolish a multi-layer substrate that includes a first metal layer, asecond layer, and optionally one or more additional layers. Suitablefirst metal layers include, for example, copper (Cu), aluminum (Al),aluminum copper (Al—Cu), aluminum silicon (Al—Si), titanium (Ti),titanium nitride (TiN), tungsten (W), tungsten nitride (WN), noblemetals (e.g., iridium (Ir), ruthenium (Ru), gold (Au), silver(Ag), andplatinum (Pt)), and combinations thereof. Suitable second layersinclude, for example, titanium (Ti), titanium nitride (TiN), tantalum(Ta), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN),oxides (e.g., silicon dioxide), low-K materials and dielectrics (e.g.,porous silica, fluorine-doped glass, carbon-doped glass, and organicpolymers), and combinations thereof. The system of the present inventionis particularly well suited for polishing a substrate comprising a firstmetal layer of copper or a copper alloy (i.e., a combination of copperand one or more metals), an adhesive layer of Ta or TaN, and one or moreoxide layers.

[0014] The liquid carrier can be any suitable carrier (e.g., solvent).Suitable liquid carriers include, for example, aqueous carriers (e.g.,water) and non-aqueous carriers. Preferably, the liquid carrier iswater.

[0015] The oxidizing agent can be any suitable oxidizing agent. Suitableoxidizing agents include, for example, one or more per-compounds, whichcomprise at least one peroxy group (—O—O—). Suitable per-compoundsinclude, for example, peroxides, persulfates (e.g., monopersulfates anddipersulfates), percarbonates, and acids thereof, and salts thereof, andmixtures thereof. Other suitable oxidizing agents include, for example,oxidized halides (e.g., chlorates, bromates, iodates, perchlorates,perbromates, periodates, and acids thereof, and mixtures thereof, andthe like), perboric acid, perborates, percarbonates, peroxyacids (e.g.,petacetic acid, perbenzoic acid, m-chloroperbenzoic acid, salts thereof,mixtures thereof, and the like), permanganates, chromates, ceriumcompounds, ferricyanides (e.g., potassium ferricyanide), mixturesthereof, and the like. Preferred oxidizing agents include, for example,hydrogen peroxide, urea-hydrogen peroxide, sodium peroxide, benzylperoxide, di-t-butyl peroxide, peracetic acid, monopersulfuric acid,dipersulfuric acid, iodic acid, and salts thereof, and mixtures thereof.

[0016] Any suitable amount of the oxidizing agent can be present in thesystem of the present invention. Preferably, the oxidizing agent ispresent in the liquid portion of the system in an amount of about 0.1-30wt. %. More preferably, the oxidizing agent is present in the liquidportion of the system in an amount of about 0.3-17 wt. %. Mostpreferably, the oxidizing agent is present in the liquid portion of thesystem in an amount of about 0.5-10 wt. %.

[0017] The polishing additive can be any suitable compound thatincreases the rate at which the system polishes at least one layer ofthe substrate. Suitable polishing additives include, for example,compounds that bind to copper. Preferably, at least one polishingadditive is an organic polishing additive. It is also preferable for thepolishing additive to be at least one compound selected from the groupconsisting of a phosphorous-containing compound, a nitrogen-containingcompound, a sulfur-containing compound, an oxygen-containing compound,and mixtures thereof.

[0018] The polishing additive can be any suitable phosphorous-containingcompound. Suitable phosphorous-containing compounds include, forexample, phosphates (e.g., pyrophosphates, tri-phosphates, condensedphosphates), phosphonic acids (e.g., mono-phosphonic acids,di-phosphonic acids, tri-phosphonic acids, poly-phosphonic acids), andsalts of phosphonic acids. Preferred phosphorous-containing compoundsinclude, for example, pyrophosphates, phosphonoacetic acid, ethylenediphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, andmixtures thereof. Preferred phosphorous-containing compounds alsoinclude, for example, M_(n) ⁺¹H_(3-n)PO₄ and M_(m) ⁺¹H_(4-m)P₂O₇,wherein M⁺¹ is a cationic species (e.g., Na, K, Cs, Rb, NH₄ ⁺), n=0-3,and m=0-4. Moreover, a preferred phosphorous-containing compound isR—O—PO₃, wherein R is an organic moiety selected from the groupconsisting of alkyl, aryl, cyclic, and aromatic groups having from 1-18carbon atoms.

[0019] The polishing additive also can be any suitablenitrogen-containing compound. Suitable nitrogen-containing compoundscomprise, for example, one or more groups selected from amines, amides,amino acids, imines, imides, imino acids, nitriles, nitros (R—NO₂), andmixtures thereof. Accordingly, suitable nitrogen-containing compoundscan comprise, for example, one or more groups selected from primaryamines, secondary amines, tertiary amines, amino alcohols, hydroxylatedamines, and mixtures thereof.

[0020] Preferably, at least one polishing additive comprises thestructure XY—NCR¹R²CR³R⁴N—X′Y′, wherein X, Y, X′, Y′, R¹, R², R³, and R⁴are selected from the group consisting of hydrogen (H) atoms,heteroatom-containing functional groups, alkyl groups,heteroatom-containing alkyl groups, cyclic groups, heteroatom-containingcyclic groups, aromatic groups, heteroatom-containing aromatic groups,and combinations thereof. More preferably, at least one polishingadditive comprises the structure XY—NCR¹R²CR³R⁴N—X′Y′, wherein X and X′are H atoms, and wherein Y, Y′, R¹, R², R³, and R⁴ are selected from thegroup consisting of hydrogen (H) atoms, heteroatom-containing functionalgroups, alkyl groups, heteroatom-containing alkyl groups, cyclic groups,heteroatom-containing cyclic groups, aromatic groups,heteroatom-containing aromatic groups, and combinations thereof. Evenmore preferably, at least one polishing additive comprises the structureXY—NCR¹R²CR³R⁴N—X′Y′, wherein X, Y, X′, and Y′ are H atoms, and whereinR¹, R², R³, and R⁴ are selected from the group consisting of hydrogen(H) atoms, heteroatom-containing functional groups, alkyl groups,heteroatom-containing alkyl groups, cyclic groups, heteroatom-containingcyclic groups, aromatic groups, heteroatom-containing aromatic groups,and combinations thereof. In this regard, nitrogen-containing compoundsthat consist of primary amine groups are preferred overnitrogen-containing compounds that comprise secondary amine groupsand/or tertiary amine groups, alone or in combination with primary aminegroups. Moreover, it is suitable for at least one polishing additive tocomprise the structure as described above, wherein the structure is inthe form of a polymer comprising about four or more (e.g., about 10 ormore, about 15 or more, about 20 or more, about 30 or more, about 40 ormore, or even about 50 or more) dissimilar, similar, or even identicaladjoined structures. Most preferably, the nitrogen-containing compoundis selected from the group consisting of polyethylenimine,1,3-diamino-2-propanol, iminodiacetic acid, 2-amino-i-butanol,ethylenediamine, aminoethylethanolamine, 2,2′-aminoethoxyethanol, andmixtures thereof.

[0021] “Heteroatom” is defined herein as any atom other than carbon andhydrogen atoms. Suitable heteroatom-containing functional groupsinclude, for example, hydroxyl groups, carboxylic acid groups, estergroups, ketone groups, amino groups (e.g., primary, secondary, andtertiary amino groups), amido groups, imido groups, thiol ester groups,thioether groups, nitrile groups, nitros groups, halogen groups, andcombinations thereof. “Alkyl groups” are defined herein as any suitablealkyl group (e.g., a C₁-C₃₀ alkyl group, a C₁-C₂₄ alkyl group, a C₁-C₁₈alkyl group, a C₁-C₁₂ alkyl group, or even a C₁-C₆ alkyl group) such as,for example, linear, branched, cyclic, saturated or unsaturated,aromatic or heteroaromatic alkyl groups. “Cyclic groups” are definedherein as any suitable cyclic group (e.g., a cyclic group having 4-20members, such as a C₄-C₂₀ cyclic group).

[0022] The polishing additive can be any suitable sulfur-containingcompound. Suitable sulfur-containing compounds include, for example,thiols, thioesters, thioethers, (R′C)(O)(SR″) carbothiolic acids,(RC)(O)(SH) carbothionic acids, (RCS)(OH) thiocarboxylic acids, sulfonicacids, thiosalicylic acids, salts thereof and mixtures thereof, whereinR, R′ and R″ are selected from the group consisting of alkyl, aryl,cyclic, and aromatic groups having from 1-18 carbon atoms. Preferredsulfur-containing compounds include, for example, thiodiacetic acid,thiosalicylic acids, and a mixture thereof.

[0023] The polishing additive can be any suitable oxygen-containingcompound. Suitable oxygen-containing compounds include, for example,hydroxylates, carbonylates, carboxylates, and acids thereof. Suitablecarboxylic acids include, for example, di-carboxylic acids,tri-carboxylic acids, and poly-carboxylic acids. Preferredoxygen-containing compounds include, for example, malonic acid, oxalicacid, citric acid, tartaric acid, succinic acid, malic acid, adipicacid, salts thereof, and mixtures thereof.

[0024] Suitable polishing additives also include one or more compoundsselected from the group consisting of (i) compounds that are bothphosphorous-containing compounds and nitrogen-containing compounds, (ii)compounds that are both phosphorous-containing compounds andsulfur-containing compounds, (iii) compounds that are bothnitrogen-containing compounds and sulfur-containing compounds, and (iv)compounds that are phosphorous-containing compounds, nitrogen containingcompounds, and sulfur-containing compounds. Preferred polishingadditives include, for example, compounds selected from the groupconsisting of 2-aminoethylphosphonic acid, amino(trimethylenephosphonicacid), diethylenetriaminepenta(methylenephosphonic acid),hexamethylenediaminetetra(methylenephosphonic acid), and mixturesthereof. Moreover, preferred polishing additives include, for example,phosphonic compounds containing primary, secondary and/or tertiaryamines, such as, for example, N-(phosphonomethyl)iminodiacetic acid,2-aminoethyl dihydrogen phosphate, 2-aminoethylphosphonic acid,2-aminoethylphosphonic acid, aminotri(methylenephosphonic acid) (i.e.,Dequest® 2000 product), 1-hydroxyethylidene-1,1-diphosphonic acid (i.e.,Dequest® 2010 product), and diethylenetriaminepenta(methylenephosphonicacid) (i.e., Dequest® 2060 product).

[0025] The polishing additive can be present in the system of thepresent invention in any suitable concentration. Preferably, thepolishing additive is present in the liquid portion of the system in anamount ranging from about 0.05-10 wt. %. More, preferably, the polishingadditive is present in the liquid portion of the system in an amountranging from about 0.3-5 wt. %.

[0026] The system of the present invention also can comprise anysuitable stopping compound. Suitable stopping compounds include, forexample, any suitable compound that inhibits the ability of the systemto polish at least a portion of one or more layers of a multi-layersubstrate. Suitable stopping compounds interact with (e.g., adhere to)the first metal layer, the second layer, and/or the one or moreadditional layers of a multi-layer substrate as described above and atleast partially inhibit the removal of the layer(s) by the system of thepresent invention. Preferably, the stopping compound interacts with(e.g., adheres to) a second layer of a multi-layer substrate asdescribed above and at least partially inhibits the removal of thesecond layer by the system. The term “at least partially inhibits” asused herein means that the system has a polishing selectivity of thefirst metal layer:second layer (e.g., Cu:Ta/TaN) of at least about 10:1,preferably at least about 30:1, more preferably at least about 50:1, andmost preferably at least about 100:1.

[0027] The stopping compound can be any suitable cationically chargednitrogen-containing compound selected from the group of compoundscomprising amines, imines, amides, imides, polymers thereof, andmixtures thereof. The term “cationically charged” as used herein meansthat a portion (e.g., about 5% or more, about 10% or more, about 15% ormore, or about 20% or more) of the stopping compound in the liquidportion of the system is in cationic form at the operating pH of thesystem of the present invention. Preferably, the stopping compound has apK_(a) value that is 1 or more units greater than the operating pH ofthe liquid portion of the system. For example, in a system with a pH of6.5, preferred stopping compounds would have a pK_(a) value of about 7.5or more. Preferred stopping compounds also are oppositely charged fromthe surface charge of the second layer of the substrate layer. Suitablestopping compounds include, for example, compounds comprising primaryamines, secondary amines, tertiary amines, quaternary amines (i.e.,quaternary ammonium salts), etheramines, oligomeric amines, oligomericimines, oligomeric amides, oligomeric imides, polymeric amines,polymeric imines, polymeric amides, polymeric imides, or mixturesthereof. Moreover, suitable stopping compounds include, for example,amino acids, amino alcohols, amino ether alcohols, or mixtures thereof.Preferred stopping compounds also include, for example, polyetheramines,polyethylenimines, N₄-amino(N,N′-bis[3-aminopropyl]ethylenediamine),4,7,10-trioxatridecane-1,13-diamine,3,3-dimethyl-4,4-diaminodicyclohexylmethane, 2-phenylethylamine,N,N-dimethyldipropylenetriamine, 3-[2-methoxyethoxy]propylamine,dimethylaminopropylamine, 1,4-bis(3-aminopropyl)piperazine, and mixturesthereof. In addition, preferred stopping compounds include, for example,isophoronediamine, hexamethylenediamine, cyclohexyl-1,3-propanediamine,thiomicamine, (aminopropyl)-1,3-propanediamine, tetraethylenepentamine,tetramethylbutanediamine, propylamine, diaminopropanol, aminobutanol,(2-aminoethoxy)ethanol, or mixtures thereof.

[0028] The stopping compound can be present in the system of the presentinvention in any suitable concentration. It is suitable, for example,for the stopping compound to be present in the liquid portion of thesystem in a concentration of about 5 wt. % or less (e.g., about 0.001-5wt. %). Preferably, the stopping compound is present in the liquidportion of the system in a concentration of about 3 wt. % or less (e.g.,about 0.05 to about 3 wt. %).

[0029] The system of the present invention can comprise any suitablecombination of at least one polishing additive and at least one stoppingcompound. For example, the system can comprise polyethylenimine and atleast one polishing additive selected from the group consisting of acarboxylic acid (preferably, a di-, tri-, or poly-carboxylic acid), aphosphate (preferably, a pyrophosphate, a tri-phosphate, or a condensedphosphate), an acid thereof, and a phosphonic acid (preferably, a di-,tri-, or poly-phosphonic acid). The system also can comprise at leastone polishing additive selected from the group consisting of acarboxylic acid (preferably, a di-, tri-, or poly-carboxylic acid), aphosphate (preferably, a pyrophosphate, a tri-phosphate, or a condensedphosphate), an acid thereof, and a phosphonic acid (preferably, a di-,tri-, or poly-phosphonic acid) and at least one stopping compoundcomprising two or more, three or more, four or more, five or more, oreven six or more nitrogen atoms (e.g., at least one stopping compoundcomprising two or more primary amine groups, at least one stoppingcompound comprising two or more amino groups and 4 or more carbon atoms,or at least one stopping compound comprising two or more primary aminegroups containing 3 or more carbon atoms). Moreover, the system cancomprise at least one polishing additive selected from the groupconsisting of a carboxylic acid (preferably, a di-, tri-, orpoly-carboxylic acid), a phosphate (preferably, a pyrophosphate, atri-phosphate, or a condensed phosphate), an acid thereof, and aphosphonic acid (preferably, a di-, tri-, or poly-phosphonic acid) and aquaternary ammonium salt comprising the structure NR¹R²R³R⁴, wherein R¹,and R² are methyl groups and R³ and R⁴ are selected from the groupconsisting of hydrogen (H) atoms, heteroatom-containing functionalgroups, alkyl groups, heteroatom-containing alkyl groups, cyclic groups,heteroatom-containing cyclic groups, aromatic groups,heteroatom-containing aromatic groups, and combinations thereof Inaddition, the system can comprise at least one polishing additiveselected from the group consisting of a carboxylic-acid (preferably, adi-, tri-, or poly-carboxylic acid), a phosphate (preferably, apyrophosphate, a tri-phosphate, or a condensed phosphate), an acidthereof, and a phosphonic acid (preferably, a di-, tri-, orpoly-phosphonic acid) and at least one stopping compound comprising anaminopropyl group and/or at least one stopping compound having amolecular weight (MW) of about 80 or more (e.g., a MW of about 100 ormore, a MW of about 250 or more). Furthermore, the system can comprise aperoxide, aminotri(methylenephosphonic acid), and1,4-bis(3-aminopropyl)piperazine, and optionally, at least onepassivation film forming agent comprising one or more 5-6 memberheterocyclic nitrogen-containing rings. The system also can comprise aperoxide, tartaric acid, and a polyethylenimine, and, optionally, atleast one passivation film forming agent comprising one or more 5-6member heterocyclic nitrogen-containing rings.

[0030] The system of the present invention can comprise any suitablepolishing pad and/or abrasive. It is suitable, for example, for thesystem of the present invention to comprise a polishing pad (e.g., anabrasive pad or a non-abrasive pad) and/or an abrasive that is suspendedin the liquid carrier (e.g., water) of the system, thereby being a partof the liquid portion of the system. Moreover, it is suitable for thesystem of the present invention to comprise a polishing pad (e.g., anabrasive pad or a non-abrasive pad), wherein no abrasive is suspended inthe liquid carrier of the system.

[0031] The polishing pad can be any suitable abrasive or non-abrasivepad. Suitable polishing pads are described, for example, in U.S. Pat.Nos. 5,849,051 and 5,849,052. Suitable polishing pads also include, forexample, woven and non-woven polishing pads. Moreover, suitablepolishing pads can comprise any suitable polymer of varying density,hardness, thickness, compressibility, ability to rebound uponcompression, and compression modulus. Suitable polymers include, forexample, polyvinylchloride, polyvinylfluoride, nylon, fluorocarbon,polycarbonate, polyester, polyacrylate, polyether, polyethylene,polyamide, polyurethane, polystyrene, polypropylene, and coformedproducts thereof, and mixtures thereof. When an abrasive is fixed (e.g.,embedded), in whole or in part, in or on the polishing pad of thesystem, such fixation on the polishing pad can be accomplished in anysuitable manner.

[0032] Suitable abrasives include, for example, metal oxide abrasives,such as, for example, alumina, silica, titania, zirconia, germania,ceria, and co-formed products thereof, and mixtures thereof. Theabrasives can be fumed products. Preferably, the abrasive of the systemis alumina (e.g., fumed alumina) and/or silica (e.g., fumed silica).

[0033] The abrasive, as described above, can be fixed, in whole or inpart, in or on the polishing pad of the system. Moreover, the abrasivecan be present in the liquid portion of the system in any suitableamount. Preferably, the abrasive is present in the liquid portion of thesystem in an amount of about 0.1-30 wt. %. More preferably, the abrasiveis present in the liquid portion of the system in an amount of about0.5-6 wt. %.

[0034] The system of the present invention further may comprise one ormore additional additives that improve or enhance the performance of thesystem. Suitable additional additives include, for example, passivationfilm-forming additives, polymeric compounds that reduce the polishingrate of at least one layer of the substrate, dispersants, surfactants,stabilizers, pH adjusters, regulators, buffers, and/or other additivesthat promote and/or control the polishing of metals and oxides. Suchadditional additives are known to those of skill in the art.

[0035] Suitable passivation film-forming agents include, for example anycompound, or mixture of compounds, that facilitates the formation of apassivation layer (i.e., a dissolution-inhibiting layer) on a metallayer and/or a metal oxide layer. Suitable passivation film-formingagents include, for example, nitrogen-containing heterocyclic compounds.Preferably, the passivation film-forming agent comprises one or more 5-6member heterocyclic nitrogen-containing rings. More preferably, thepassivation film-forming agent is selected from the group consisting of1,2,3-riazole, 1,2,4-riazole, benzotriazole, benzimidazole,benzothiazole, and derivatives thereof, such as, for example, hydroxy-,amino-, imino-, carboxy-, mercapto-, nitro-, urea-, thiourea-, oralkyl-substituted derivatives thereof. Most preferably, the passivationfilm-forming agent is selected from the group consisting ofbenzotriazole (BTA), 1,2,3-triazole, 1,2,4-triazole, and mixturesthereof.

[0036] The passivation film-forming agent can be present in the systemof the present invention in any suitable concentration. Preferably, thepassivation film-forming agent is present in the liquid portion of thesystem in an amount of about 0.005-1 wt. %. Preferably, the passivationfilm-forming agent is present in the liquid portion of the system in anamount of about 0.01-0.2 wt. %.

[0037] The system of the present invention further can comprise a sourceof ammonia (e.g., ammonia or an ammonium salt). Ammonia and/or ammoniumsalts enhance the removal rate and/or removal selectivity (e.g., Cu:Taremoval selectivity) of the system, by interacting with one or morecomponents of the system (e.g., the polishing additive). Preferably, thesystem of the present invention comprises ammonia and/or ammonium saltsand one or more polishing additives. Preferably, the system comprises asource of ammonia and at least one polishing additive selected from thegroup consisting of a carboxylic acid (preferably, a di-, tri-, orpoly-carboxylic acid), a phosphate (preferably, a pyrophosphate, atri-phosphate, or a condensed phosphate), an acid thereof, and aphosphonic acid (preferably, a di-, tri-, or poly-phosphonic acid). Forexample, the system can comprise aminotri(methylenephosphonic acid) anda source of ammonia (e.g., ammonia and/or an ammonium salt).

[0038] Suitable polymeric compounds include, for example, any suitablepolymeric compound that reduces the polishing rate of at least one layerassociated with the substrate. Preferably, the system comprises at leastone polymeric compound comprising a polyvinylalcohol, a polyethyleneoxide, a polypropylene oxide, a sulfonic acid polymer, a sulfonatepolymer, or a mixture thereof.

[0039] Suitable surfactants include, for example, cationic surfactants,anionic surfactants, nonionic surfactants, amphoteric surfactants,fluorinated surfactants, mixtures thereof, and the like. Suitable pHadjusters, regulators, or buffers include, for example, sodiumhydroxide, sodium carbonate, sulfuric acid, hydrochloric acid, nitricacid, phosphoric acid, citric acid, potassium phosphate, mixturesthereof, and the like.

[0040] The present invention also provides a method of polishing asubstrate with a system as described herein. Moreover, the presentinvention provides a method of polishing a multi-layer substrate asdescribed above with the system. The system of the present invention iscapable of polishing a substrate (e.g., a multi-layer substrate) at arelatively high rate, e.g., removing the first metal layer, the secondlayer, and/or the one or more additional layers of the substrate at arelatively high rate.

[0041] A substrate can be treated with the system of the presentinvention by any suitable technique that involves the use of a polishingpad. Preferably, the system is applied to the surface of a substrate andpolished, such that at least a portion of one or more layers of thesubstrate is removed. More preferably, the system is applied to thefirst metal layer of a multi-layer substrate that includes a first metallayer and a second layer, and the first metal layer is polished with thesystem until at least a portion of the first metal layer is removed fromthe substrate. A second polishing system, composition, and/or slurry canbe used in a subsequent polishing step to remove at least a portion of asecond layer, dielectric layer, and/or one or more additional layers ofa multi-layer substrate. Preferably, the second polishing system has agreater polishing selectivity for the second layer (e.g., Ta or TaN) ofthe multi-layer substrate than for the first metal layer (e.g., Cu) ofthe substrate. Moreover, cleaning compositions can be used after some orall successive polishing steps, in order to remove remnants of thepolished substrate and/or remnants of the polishing system, composition,and/or slurry.

[0042] It is suitable for the liquid portion of the system to beformulated prior to delivery to the polishing pad or to the surface ofthe substrate, e.g., in a batch or continuous process. It is alsosuitable for the liquid portion of the system to be formulated (e.g.,mixed) on the surface of the polishing pad or on the surface of thesubstrate, through delivery of the components of the liquid portion ofthe system from two or more distinct sources, whereby the componentsmeet at the surface of the polishing pad or at the surface of thesubstrate. In this regard, the flow rate at which the components of theliquid portion of the system are delivered to the polishing pad or tothe surface of the substrate (i.e., the delivered amount of theparticular components of the system) can be altered prior to thepolishing process and/or during the polishing process, such that thepolishing selectivity and/or viscosity of the system is altered.Moreover, it is suitable for the particular components of the liquidportion of the system being delivered from two or more distinct sourcesto have different pH values, or alternatively to have substantiallysimilar, or even equal, pH values, prior to delivery to the surface ofthe polishing pad or to the surface of the substrate. It is alsosuitable for the particular components being delivered from two or moredistinct sources to be filtered either independently or to be filteredjointly (e.g., together) prior to delivery to the surface of thepolishing pad or to the surface of the substrate.

EXAMPLES

[0043] The following examples further illustrate the present inventionbut, of course, should not be construed as in any way limiting itsscope.

[0044] The tantalum wafers referenced in all of the following examplesand the copper wafers referenced in all but one of the followingexamples (i.e., Example 4) were tantalum blanket films and copperblanket films, respectively. The silicon dioxide wafers referenced inall of the following examples were blanket films with a thickness ofapproximately 9000 Å. All blanket films were deposited on a siliconsubstrate.

[0045] The copper, tantalum, and silicon dioxide wafers in the followingexamples (hereinafter collectively referred to as “test wafers”) wereeach polished with an IPEC472 polishing machine. The polishing pads usedin all but one of the following examples (i.e., Example 4) were Rodel®IC1000 polishing pads stacked on Rodel® SUBA IV pads. The polishing padsused in Example 4 were Rodel® IC1000 polishing pads, without stackedRodel® SUBA IV pads. The test wafers in all but one of the followingexamples (i.e., Example 4) were polished using a down force of about 20kPa (3 psi), a back pressure of 0 kPa (0 psi), a table speed of 50 rpm,and a wafer holder speed of 30 rpm. The test wafers of Example 4 werepolished using a down force of about 20 kPa (3 psi), a back pressure ofabout 14 kPa (2 psi), a table speed of 55 rpm, and a wafer holder speedof 30 rpm.

[0046] Test wafer removal rates were determined by directly measuringthe thickness of each test wafer before and after polishing using aTencor Surfscan® UV 1050 machine and a Tencor RS-75.

[0047] The systems in all but one of the following examples (i.e.,Example 7) were adjusted to the target pH with ammonium hydroxide(NH₄OH), unless otherwise noted.

Example 1

[0048] This example illustrates that the polishing rate of a first metallayer achievable by the system of the present invention is dependent onthe presence and identity of the polishing additive in the system.

[0049] Copper wafers were polished separately with three differentpolishing systems (designated Systems 1A-1C) with 2 wt. % alumina(specifically, Cabot's Semi-Sperse® W-A355 product), 1 wt. % oxidizingagent (specifically, H₂O₂), 2.2 wt. % polishing additive (specifically,aminotri(methylenephosphonic acid) (i.e., Dequest® 2000 product)),either 0 M, 0.037 M, or 0.33 M ammonia (i.e., 0 wt. % NH₃, about 0.06wt. % NH₃, and about 0.56 wt. % NH₃, respectively), and 0.08 wt. %film-forming agent (specifically, triazole), wherein each of the systemswas pH-adjusted to 8.5 with HNO₃ or KOH.

[0050] For comparison purposes, the test wafers also were polished witha comparative system (“comparative”) with 2 wt. % alumina (specifically,Cabot's Semi-Sperse® W-A355 product), wt. % oxidizing agent(specifically, H₂O₂), 0.33 M ammonia (i.e., about 0.56 wt. % NH₃), and0.08 wt. % film-forming agent (specifically, triazole), wherein thesystem was pH-adjusted to 8.5 with HNO₃.

[0051] Following use of the systems, the removal rate (RR) of copper,tantalum, and SiO₂ by each system was determined, as well as therelative removal of copper to tantalum (“Cu:Ta”), with the resultingdata set forth in Table 1. TABLE 1 NH₃ Cu RR System Polishing Additive[M] [Å/min] Comparative None 0.33  180 1A 2.2 wt. % Dequest ® 2000 None1657 1B 2.2 wt. % Dequest ® 2000  0.037 2527 1C 2.2 wt. % Dequest ® 20000.33 6448

[0052] As is apparent from the data set forth in Table 1, the copperremoval rates exhibited by systems containing a polishing additive(Systems 1A-1C) were greater than the copper removal rate of thecomparative system that did not contain a polishing additive. Moreover,the copper removal rate exhibited by the system containing a polishingadditive and 0.33 M NH₃ (System 1C) was greater than the copper removalrate of the system containing a polishing additive and 0.037 M NH₃(System 1B), which, in turn, was greater than the copper removal rate ofthe system with a polishing additive and no NH₃ (System 1A).

[0053] These results demonstrate the significance of the presence of apolishing additive in the context of the present inventive system, aswell as a combination of the polishing additive with a particularconcentration of a source of ammonia, on the polishing rate achievableby the present inventive system and method.

Example 2

[0054] This example illustrates that the polishing rate of a first metallayer achievable by the system of the present invention is dependent onthe presence and identity of the polishing additive in the system.

[0055] Copper wafers were polished separately with five differentpolishing systems (designated Systems 2A-2E) with 2 wt. % alumina(specifically, Cabot's Semi-Sperse® W-A355 product), 1 wt. % oxidizingagent (specifically, H₂O₂), varying concentrations of a first polishingadditive (specifically, 0.16 M ethylenediamine, 0.33 M2-amino-1-butanol, 0.33 M aminoethylethanolamine, 0.33 M2,2′-aminoethoxyethanol, or 0.33 M of a low molecular weightethylenimine copolymer (i.e., Lupasol® FG)), 2.2 wt. % of a secondpolishing additive (specifically, aminotri(methylenephosphonic acid)(i.e., Dequest® 2000 product)), and 0.08 wt. % film-forming agent(specifically, triazole), wherein each of the systems had a pH of 8.5.Following use of the systems, the removal rate (RR) of copper by eachsystem was determined, with the resulting data set forth in Table 2. Themolecular structure of a portion of the first polishing additive of eachsystem also is included in Table 2 and the XY—NCR¹R²CR³R⁴N—X′Y′ moiety,as discussed above, is in bold in the molecular structure of Table 2, ifpresent in the polishing additive. TABLE 2 Cu RR System 1^(st) PolishingAdditive Molecular Structure [Å/min] 2A 0.16 M ethylenediamineH₂NCH₂CH₂NH₂ >15000    2B 0.33 M aminoethylethanolamineH₂NCH₂CH₂NHCH₂CH₂OH 10815  2C 0.33 M Lupasol ® FG H₂N—[CH₂CH₂NH(R)]—NH₂4985 2D 0.33 M 2,2′-aminoethoxyethanol H₂NCH₂CH₂OCH₂CH₂OH 3196 2E 0.33 M2-amino-1-butanol H₃CCH₂CH₂CH(NH₂)OH 2091

[0056] As is apparent from the data set forth in Table 2, the copperremoval rates exhibited by systems containing a polishing additive thatcomprises the XY—NCR¹R²CR³R⁴N—X′Y′ moiety (Systems 2A-2C) were greaterthan the copper removal rates of the systems that contained a polishingadditive that did not comprise the XY—NCR¹R²CR³R⁴N—X′Y′ moiety (Systems2D-2E). Moreover, among the systems containing the XY—NCR¹R²CR³R⁴N—X′Y′moiety (Systems 2A-2C), the copper removal rate exhibited by the systemin which X, Y, X′, and Y′ were hydrogen atoms (i.e., two primary aminogroups) (System 2A) was greater than the copper removal rate exhibitedby the system in which X, Y, and X′ were hydrogen atoms and Y′ wasethanol (i.e., one primary amino group and one secondary amino group)(System 2B), which, in turn, was greater than the copper removal rateexhibited by the system comprising a ratio of primary:secondary:tertiary amino groups of about 1:0.82:0.53 (System 2C).

[0057] These results demonstrate the significance a polishing additivecomprising the XY—NCR₂CR₂N—X′Y′ moiety in the context of the presentinventive system, as well as the significance of the ratio ofprimary:secondary:tertiary amino groups in the XY—NCR₂CR₂N—X′Y′ moietyof the polishing additive, on the polishing rate achievable by thepresent inventive system and method.

Example 3

[0058] This example illustrates that the polishing rate of a first metallayer achievable by the system of the present invention is dependent onthe presence and identity of the polishing additive in the system.

[0059] Copper wafers and tantalum wafers were polished separately withsixteen different polishing systems (designated Systems 3A-3P) with 3wt. % alumina (specifically, Cabot's Semi-Sperse® W-A355 product), 2.5wt. % oxidizing agent (specifically, H₂O₂), and either 0.5 wt. % or 1wt. % of a polishing additive (specifically, 1-diphosphonic acid (i.e.,Dequest® 2010 product), diethylenetriaminepenta(methylenephosphonicacid) (i.e., Dequest® 2060 product), N-phosphonomethyliminodiaceticacid, Lupasol® FG, 1,3-diamino-2-propanol, 2-imino-4-thiobiuret,iminodiacetic acid, dimethylgloxime, dipyridylamine,iminodiacetonitrile, guanidine nitrate, pyrazinecarbonitrile,thioglycolic(mercaptoacetic)acid, thiodipropanionic acid, 1 wt. % of anethoxylated high molecular weight polyethylenimine (i.e., Lupasol®SC-61B), or a modified high molecular weight ethylenimine polymer (i.e.,Lupasol® SKA)), wherein each of the systems had a pH of 5 (Systems 3C,3F, 3H, 3I, 3K, 3L, 3O, and 3P) or a pH of 7.7 (Systems 3A, 3B, 3D, 3F,3G, 3J, 3M, and 3N).

[0060] For comparison purposes, the test wafers also were polished witha control system (“control”) with 3 wt. % alumina (specifically, Cabot'sSemi-Sperse® W-A355 product) and 2.5 wt. % oxidizing agent(specifically, H₂O₂), wherein the control system had a pH of 7.7.

[0061] Following use of the systems, the removal rate (RR) of copper andtantalum by each system was determined, as well as the relative removalof copper to tantalum (“Cu:Ta”). The resulting data are set forth inTable 3. TABLE 3 Cu RR Ta RR System Polishing Additive [Å/min] [Å/min]Cu:Ta Control none  87 198  1:2 3A   1 wt. % Dequest ® 2010 4777  40612:1 3B   1 wt. % Dequest ® 2060 7624  279 27:1 3C   1 wt. %N-phosphonomethyl- 4333  314 14:1 iminodiacetic acid 3D   1 wt. %Lupasol ® FG 733  13 56:1 3E   1 wt. % 1,3-diamino-2-propanol 2668   5053:1 3F   1 wt. % 2-imino-4-thiobiuret 1216   95 13:1 3G   1 wt. %iminodiacetic acid 7738  533 15:1 3H 0.5 wt. % dimethylglyoxime 1153 273  4:1 3I 0.5 wt. % dipyridylamine 3022  264 11:1 3J   1 wt. %iminodiacetonitrile 243 446   1:1.8 3K 0.5 wt. % guanidine nitrate 281289  1:1 3L 0.5 wt. % pyrazinecarbonitrile 246 323   1:1.3 3M   1 wt. %thioglycolic- 552 263  2:1 (mercaptoacetic) acid 3N   1 wt. %thiodipropanionic acid 652 250 2.6:1  3O   1 wt. % Lupasol ® SC-61B 682 14 49:1 3P 0.5 wt. % Lupasol ® SKA 480  15 32:1

[0062] As is apparent from the data set forth in Table 3, the ratio ofcopper removal to tantalum removal (i.e., the Cu:Ta removal selectivity)exhibited by systems containing a polishing additive (Systems 3A-3D)were greater than the Cu:Ta removal selectivity of the control polishingcomposition. Moreover, the Cu:Ta removal selectivity of the systemcontaining Lupasol® FG (System 3D) was the greatest among the systems ofTable 3.

[0063] These results demonstrate the significance of the presence andidentity of the polishing additive in the context of the presentinventive system on the polishing rate and selectivity achievable by thepresent inventive system and method.

Example 4

[0064] This example illustrates that the polishing rate of a first metallayer achievable by the system of the present invention is dependent onthe presence and identity of the polishing additive in the system.

[0065] Copper wafers and tantalum wafers were polished separately withsix different polishing systems (designated Systems 4A-4F) with 5 wt. %silica (specifically, Cabot's Semi-Sperse® SC-E product), 2.5 wt. %oxidizing agent (specifically, H₂O₂), and either 0.5 wt. % or 1 wt. % ofa polishing additive (specifically, potassium pyrophosphate (K₄P₂O₇),phosphonoacetic acid, 1-di-phosphonic acid (i.e., Dequest® 2010product), aminotri(methylenephosphonic acid) (i.e., Dequest® 2000product), a low molecular weight ethylenimine copolymer (i.e., Lupasol®FG), or a high molecular weight ethylene-imine homopolymer (i.e.,Lupasol® P)), wherein each of the systems had a pH of 5 (Systems 4A, 4D,4E, and 4F) or a pH of 7.7 (Systems 4B and 4C).

[0066] For comparison purposes, the test wafers also were polished witha control system (“control”) with 5 wt. % silica (specifically, Cabot'sSemi-Sperse® SC-E product), 2.5 wt. % oxidizing agent (specifically,H₂O₂), wherein the control system had a pH of 7.7.

[0067] Following use of the systems, the removal rate (RR) of copper andtantalum by each system was determined, as well as the relative removalof copper to tantalum (“Cu:Ta”). The resulting data are set forth inTable 4. TABLE 4 Cu RR Ta RR System Polishing Additive [Å/min] [Å/min]Cu:Ta Control none  306 383   1:1.3 4A 0.5 wt. % K₄P₂O₇ 3918 798  5:1 4B0.5 wt.% phosphonoacetic acid 3658  40 91:1 4C 0.5 wt. % Dequest ® 20102532  66 38:1 4D 0.5 wt. % Dequest ® 2000 5245 337 16:1 4E   1 wt. %Lupasol ® FG 5784  9 643:1  4F   1 wt. % Lupasol ® P 4297  5 860:1 

[0068] As is apparent from the data set forth in Table 4, the ratio ofcopper removal to tantalum removal (i.e., the Cu:Ta removal selectivity)exhibited by systems containing a polishing additive (Systems 4A-4F)were greater than the Cu:Ta removal selectivity of the control polishingcomposition. Moreover, the Cu:Ta removal selectivity of the systemcontaining Lupasol® FG and Lupasol® P (Systems 4E and 4F, respectively)was greater than the Cu:Ta removal selectivities of the systemscontaining K₄P₂O₇, phosphonoacetic acid, Dequest® 2010, and Dequest®2000 (Systems 4A, 4B, 4C, and 4D, respectively).

[0069] These results demonstrate the significance of the presence andidentity of the polishing additive in the context of the presentinventive system on the polishing rate and selectivity achievable by thepresent inventive system and method.

Example 5

[0070] This example illustrates that the polishing selectivity of amulti-layer substrate achievable by the system of the present inventionis dependent on the presence and identity of the polishing additive andstopping compound in the system.

[0071] Copper wafers, tantalum wafers, and silicon dioxide (SiO₂) waferswere polished separately with eight different polishing systems(designated Systems 5A-5G) with 3 wt. % alumina (specifically, Cabot'sSemi-Sperse® W-A355 product), 2.5 wt. % oxidizing agent (specifically,H₂O₂), varying concentrations of a polishing additive (specifically,1.25 wt. % tartaric acid, 0.5 wt. % 1-di-phosphonic acid (i.e., Dequest®2010 product), 0.75 wt. % aminotri(methylenephosphonic acid) (i.e.,Dequest® 2000 product), 0.8 wt. % Dequest® 2010 product, or 2.5 wt. %Dequest® 2000 product), and varying concentrations of a stoppingcompound (specifically, 0.25 wt. % Lupasol® SKA, which contains 25% ofan ethylenimine polymer (i.e., 0.06 wt. % polyethylenimine), 0.1 wt. %dicyanoimidazole, 0.5 wt. % Lupasol SKA (i.e., 0.12 wt. %polyethylenimine), 0.5 wt. % polyacylamide, or 0.5 wt. %1,4-bis(3-aminopropyl) piperazine, or 0.5 wt. % Varisoft® 300, whichcontains cetyl trimethylammonium chloride), wherein each of the systemshad a pH of 5 (System 5E) or a pH of 7.7 (Systems 5A-5D, 5F-5G).Moreover, System 5C contained 0.005 wt. % surfactant (specifically,Triton DF-16).

[0072] For comparison purposes, the test wafers also were polished witha control system (“control”) with 3 wt. % alumina (specifically, Cabot'sSemi-Sperse® W-A355 product) and 2.5 wt. % oxidizing agent(specifically, H₂O₂), wherein the control system had a pH of 7.7.Moreover, also for comparison purposes, the test wafers were polishedwith (i) a comparative system (“comparative 1”) with 3 wt. % alumina(specifically, Cabot's Semi-Sperse® W-A355 product), 2.5 wt. % oxidizingagent (specifically, H₂O₂), and 1.25 wt. % polishing additive(specifically, tartaric acid), and with (ii) a comparative system(“comparative 2”) with 3 wt. % alumina (specifically, Cabot'sSemi-Sperse® W-A355 product), 2.5 wt. % oxidizing agent (specifically,H₂O₂), and 1 wt. % polishing additive (specifically, Dequest® 2010product), wherein each of the comparative systems had a pH of 7.7.

[0073] Following use of the systems, the removal rate (RR) of copper,tantalum, and SiO₂ by each system was determined, as well as therelative removal of copper to tantalum (“Cu:Ta”). The resulting data areset forth in Table 5. TABLE 5 Polishing Stopping Cu RR Ta RR SiO₂ RRSystem Additive Compound [Å/min] [Å/min] [Å/min] Cu:Ta Control none none 87 198 —  1:2 Comparative 1.25 wt. % none 3615 133 53 27:1 1 tartaricacid Comparative   1 wt. % none 4777 406 — 12:1 2 Dequest ® 2010 5A 1.25wt. % 0.06 wt. % 2375  19 12 125:1  tartaric acid polyethylenimine 5B 0.5 wt. % 0.1 wt. % dicyano- 3163 175 54 18:1 Dequest ® imidazole 20105C 0.75 wt. % 0.12 wt. % 3265  28 16 117:1  Dequest ® polyethylenimime2000 5D  0.8 wt. % 0.12 wt. % 2949  35 26 84:1 Dequest ®polyethylenimine 2010 5E 0.75 wt. % 0.5 wt. % 6381  43 28 148:1 Dequest ® polyacylamide 2000 5F  2.5 wt. % 0.5 wt. % 1,4-bis- 3860 109  5.5 35:1 Dequest ® (3-aminopropyl) 2000 piperazine 5G  2.5 wt. % 0.5wt. % 2260   97.6   3.6 23:1 Dequest ® Varisoft ® 300 2000

[0074] As is apparent from the data set forth in Table 5, the ratio ofcopper removal to tantalum removal (i.e., the Cu:Ta removal selectivity)exhibited by systems containing a polishing additive and a stoppingcompound (Systems 1A-1G) were greater than the Cu:Ta removal selectivityof both the control polishing system and of the comparative 2 polishingsystem, and were similar to or greater than the Cu:Ta removalselectivity of the comparative 1 polishing system. Moreover, the SiO₂removal rate exhibited by systems containing a polishing additive and astopping compound (Systems 1A-1G) were similar to or less than the SiO₂removal rate exhibited by the comparative 1 polishing system.

[0075] These results demonstrate the significance of the combination ofa polishing additive and a stopping compound in the context of thepresent inventive system, as well as the effect of the particularpolishing additive, in combination with the particular stoppingcompound, on the polishing rate and selectivity achievable by thepresent inventive system and method.

Example 6

[0076] This example illustrates that the polishing selectivity of amulti-layer substrate achievable by the system of the present inventionis dependent on the presence and identity of the polishing additive andstopping compound in the system.

[0077] Copper wafers, tantalum wafers, and silicon dioxide (SiO₂) waferswere polished separately with three different polishing systems(designated Systems 2A-2C) with 5 wt. % silica (specifically, Cabot'sCab-O-Sperse® SC-E product), 2.5 wt. % oxidizing agent (specifically,H₂O₂), varying concentrations of a polishing additive (specifically, 0.8wt. % 1-di-phosphonic acid (i.e., Dequest® 2010 product), 0.75 wt. %aminotri(methylenephosphonic acid) (i.e., Dequest® 2000 product), or0.75 wt. % diethylenetriaminepenta(methylenephosphonic acid) (i.e.,Dequest® 2060 product)), and 0.5 wt. % stopping compound (specifically,0.5 wt. % Lupasol® SKA, which contains 25% of an ethylenimine polymer(i.e., 0.12 wt. % polyethylenimine)), wherein each of the systems had apH of 7.7. For comparison purposes, the test wafers also were polishedwith a control system (“control”) with 5 wt. % silica (specifically,Cabot's Cab-O-Sperse® SC-E product) and 2.5 wt. % oxidizing agent(specifically, H₂O₂), wherein the control system had a pH of 8.Following use of the systems, the removal rate (RR) of copper, tantalum,and SiO₂ by each system was determined, as well as the relative removalof copper to tantalum (“Cu:Ta”), with the resulting data set forth inTable 6. TABLE 6 Polishing Stopping Cu RR Ta RR SiO₂ RR System AdditiveCompound [Å/min] [Å/min] [Å/min] Cu:Ta Control none none  306 383  299    1:1.3 6A 0.8 wt. % 0.12 wt. % 1789 13   5 138:1 Dequest ® Lupasol ®2010 SKA 6B 0.75 wt. % 0.12 wt. % 1733 9 20 193:1 Dequest ® Lupasol ®2000 SKA 6C 0.75 wt. % 0.12 wt. % 2132 7 12 305:1 Dequest ® Lupasol ®2060 SKA

[0078] As is apparent from the data set forth in Table 6, the ratio ofcopper removal to tantalum removal (i.e., the Cu:Ta removal selectivity)exhibited by systems containing a polishing additive and a stoppingcompound (Systems 6A-6C) were greater than the Cu:Ta removal selectivityof the control system that did not contain a polishing additive or astopping compound. Moreover, the copper removal rate and the Cu:Taremoval selectivity of the system containing a stopping compound andDequest® 2060 product (System 6C) were greater than the copper removalrate and the Cu:Ta removal selectivity of the system containing astopping compound and Dequest® 2000 product (System 6B), which in turnwere greater than the copper removal rate and the Cu:Ta removalselectivity of the system containing a stopping compound and Dequest®2010 product (System 6A). Moreover, the SiO₂ removal rate exhibited bysystems containing a polishing additive and a stopping compound (Systems6A-6C) were greater than the SiO₂ removal rate of the control systemthat did not contain a polishing additive or a stopping compound.

[0079] These results demonstrate the significance of the combination ofa polishing additive and a stopping compound in the context of thepresent inventive system, as well as the effect of the particularpolishing additive, in combination with the stopping compound, on thepolishing rate and selectivity achievable by the present inventivemethod.

Example 7

[0080] This example illustrates that the polishing selectivity of amulti-layer substrate achievable by the system of the present inventionis dependent on the identity of the stopping compound in the system.

[0081] Copper wafers, tantalum wafers, and silicon dioxide (SiO₂) waferswere polished separately with fourteen different polishing compositionswith 3 wt. % alumina (specifically, Cabot's Semi-Sperse® W-A355product), 2.5 wt. % oxidizing agent (specifically, H₂O₂), 1 wt. %polishing additive (specifically, ammonium oxalate ((NH₄)₂C₂O₄)), andvarying concentrations of a stopping compound (specifically, 0.2 wt. %isophoronediamine, 0.2 wt. % hexamethylenediamine, 0.2 wt. %N-cyclohexyl-1,3-propanediamine, 0.2 wt. %N-(3-aminopropyl)-1,3-propanediamine, 0.2 wt. % tetraethylenepentamine,0.2 wt. % N,N,N′,N′-tetramethyl-1,4-butanediamine, 0.5 wt. %propylamine, 0.2 wt. % 2-(2-aminoethoxy)ethanol, 2.0 wt. %1,3-diamino-2-propanol, 1.0 wt. % thiomicamine, 3.0 wt. %2-amino-1-butanol, 0.2 wt. % 4,7,10-trioxa-1,13-tridecanediamine, 0.2wt. % lysine, 0.2 wt. %poly[bis(2-chloroether)-alt-1,3-bis(3-dimethylamino)propyl]), whereineach of the systems had a pH of 7.6. For comparison purposes, the testwafers also were polished with a control system (“control”) with 3 wt. %alumina (specifically, Cabot's Semi-Sperse® W-A355 product), 2.5 wt. %oxidizing agent (specifically, H₂O₂), and 1 wt. % polishing additive(specifically, ammonium oxalate (NH₄)₂C₂O₄), wherein the control systemhad a pH of 7.6. Following use of the polishing compositions, therelative tantalum (Ta) removal rate and the relative silicon dioxide(SiO₂) removal rate of each system were determined in comparison withthe removal rates of the control system, with the resulting data setforth in Table 7. TABLE 7 Relative Relative Removal Rate Removal SystemStopping Compound Ta Rate SiO₂ Control none 1   1   7A 0.2 wt. %isophoronediamine 0.17 — 7B 0.2 wt. % hexamethylenediamine 0.24 0.27 7C0.2 wt. % N-cyclohexyl- 0.12 0.11 1,3-propanediamine) 7D 0.2 wt. %N-(3-aminopropyl)-1,3- 0.17 0.03 propanediamine 7E 0.2 wt. %tetraethylenepentamine 0.21 0.13 7F 0.2 wt. % N,N,N′,N′-tetramethyl- —0.37 1,4-butanediamine 7G 0.5 wt. % propylamine 0.17 — 7H 0.2 wt. %2-(2-aminoethoxy)- 0.71 — ethanol 7I 3.0 wt. % 2-amino-1-butanol 0.040.21 7J 0.2 wt. % 4,7,10-trioxa-1,13- 0.28 0.22 tridecanediamine 7K 0.2wt. % lysine 0.35 1.1  7L 0.2 wt. % poly[bis(2-chloroether)-alt-1,3-bis(3- — 0.33 dimethylamino)propyl]

[0082] As is apparent from the data set forth in Table 7, the relativetantalum removal rates exhibited by the evaluated polishing systemscontaining a polishing additive and a stopping compound were desirablyless than the relative tantalum removal rate of the control polishingcomposition that did not contain both a polishing additive and astopping compound. Moreover, the relative SiO₂ removal rates exhibitedby all but one of the evaluated polishing systems containing a polishingadditive and a stopping compound were desirably less than the relativeSiO₂ removal rate of the control polishing system that did not containboth a polishing additive and a stopping compound.

[0083] These results demonstrate the significance of the presence of astopping compound in the context of the present inventive system, aswell as the effect of the particular stopping compound, on the removalrate and selectivity achievable by the present inventive method.

Example 8

[0084] This example illustrates that the polishing selectivity of amulti-layer substrate achievable by the system of the present invention,as well as the minimization of surface defects by the system, isdependent on the identity of the stopping compound in the system.

[0085] Copper wafers, tantalum wafers, and silicon dioxide (SiO₂) waferswere polished separately with two different polishing systems(designated Systems 8A and 8B) with 3 wt. % alumina (specifically,Cabot's Semi-Sperse® W-A355 product), 2.5 wt. % oxidizing agent(specifically, H₂O₂), 1.25 wt. % polishing additive (specifically,tartaric acid), and either 0 wt. % or 0.06 wt. % stopping compound(specifically, an ethylenimine polymer (i.e., Lupasol® SKA)), whereineach of the systems had a pH of 7.7. Following use of the systems, therelative removal of copper to tantalum (“Cu:Ta”), copper dishing, andSiO₂ erosion were measured, with the resulting data set forth in Table8. Wafer dishing of copper lines (i.e., copper dishing) and SiO₂ erosionwere determined through use of a Tencor P-20 Long Scan Profiler. Copperdishing was measured at a 10 μm feature size and at a 50 μm feature size(“10 μm/50 μm”). SiO₂ erosion was measured for an array having a 2 μmline and a 4 μm pitch (“2 μm/4 μm array”). TABLE 8 SiO₂ ErosionPolishing Stopping Cu Dishing [2 μm/4 μm System Additive Compound Cu:Ta[10 μm/50 μm] array] 8A 1.25 wt. % None  81:1 952 Å/1868 Å 896 Åtartaric acid 8B 1.25 wt. % 0.06 wt. % tartaric acid Lupasol ® 220:1 840Å/1552 Å 714 Å SKA

[0086] As is apparent from the data set forth in Table 8, the ratio ofcopper removal to tantalum removal (i.e., the Cu:Ta removal selectivity)exhibited by the system containing a polishing additive and a stoppingcompound (System 8B) were greater than the Cu:Ta removal selectivityexhibited by the system containing only a polishing additive (System8A). Moreover, Cu dishing and SiO₂ erosion exhibited by the systemcontaining a polishing additive and a stopping compound (System 4B) wereless than the Cu dishing and SiO₂ erosion exhibited by the systemcontaining only a polishing additive (System 8A).

[0087] These results demonstrate the significance of the presence of astopping compound in the context of the present inventive system on thepolishing selectivity achievable by the system, as well as theminimization of surface defectivity of the polished substrate by thesystem of the present invention.

[0088] All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

[0089] The use of the terms “a” and “an” and “the” and similar referentsin the context of describing the invention (especially in the context ofthe following claims) are to be construed to cover both the singular andthe plural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

[0090] Preferred embodiments of this invention are described herein,including the best mode known to the inventors for carrying out theinvention. Variations of those preferred embodiments may become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventors expect skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than as specifically described herein.Accordingly, this invention includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by theinvention unless otherwise indicated herein or otherwise clearlycontradicted by context.

What is claimed is:
 1. A system for polishing one or more layers of amulti-layer substrate that includes a first metal layer and a secondlayer comprising (i) a liquid carrier, (ii) at least one oxidizingagent, (iii) at least one polishing additive that increases the rate atwhich the system polishes at least one layer of the substrate, whereinthe polishing additive is selected from the group consisting ofpyrophosphates, condensed phosphates, phosphonic acids and saltsthereof, amines, amino alcohols, amides, imines, imino acids, nitrites,nitros, thiols, thioesters, thioethers, carbothiolic acids, carbothionicacids, thiocarboxylic acids, thiosalicylic acids, and mixtures thereof,and (iv) a polishing pad and/or an abrasive.
 2. The system of claim 1,wherein the liquid carrier is a nonaqueous solvent.
 3. The system ofclaim 1, wherein the liquid carrier is water.
 4. The system of claim 3,wherein the system comprises an abrasive suspended in the liquidcarrier.
 5. The system of claim 3, wherein the abrasive is fixed on thepolishing pad.
 6. The system of claim 3, wherein no abrasive is presentin the system, and the polishing pad is a non-abrasive pad.
 7. Thesystem of claim 3, wherein at least one polishing additive is selectedfrom the group consisting of di-phosphonic acids, tri-phosphonic acids,poly-phosphonic acids, phosphonoacetic acids, and mixtures thereof. 8.The system of claim 7, wherein at least one oxidizing agent is aperoxide, and wherein the system further comprises at least onepassivation film forming agent comprising one or more 5-6 memberheterocyclic nitrogen-containing rings.
 9. The system of claim 7,wherein at least one polishing additive is selected from the groupconsisting of ethylene di-phosphonic acid,1-hydroxyethylidene-1,1-di-phosphonic acid, and a mixture thereof. 10.The system of claim 3, wherein at least one polishing additive isselected from the group consisting of primary amines, secondary amines,tertiary amines, hydroxylated amines, and mixtures thereof.
 11. Thesystem of claim 10, wherein at least one polishing additive comprisesthe structure XY—NCR¹R²CR³R⁴N—X′Y′, wherein X, Y, X′, Y′, R¹, R², R³,and R⁴ are selected from the group consisting of hydrogen (H) atoms,heteroatom-containing functional groups, C₁-C₂₀ alkyl groups,heteroatom-containing C₁-C₂₀ alkyl groups, cyclic groups,heteroatom-containing cyclic groups, aromatic groups,heteroatom-containing aromatic groups, and combinations thereof.
 12. Thesystem of claim 11, wherein at least one polishing additive comprisesthe structure XY—NCR¹R²CR³R⁴N—X′Y′, wherein X and X′ are H atoms, andwherein Y, Y′, R¹, R², R³, and R⁴ are selected from the group consistingof hydrogen (H) atoms, heteroatom-containing functional groups, alkylgroups, heteroatom-containing alkyl groups, cyclic groups,heteroatom-containing cyclic groups, aromatic groups,heteroatom-containing aromatic groups, and combinations thereof.
 13. Thesystem of claim 12, wherein at least one polishing additive comprisesthe structure XY—NCR¹R²CR³R⁴N—X′Y′, wherein X, Y, X′, and Y′ are Hatoms, and wherein R¹, R², R³, and R⁴ are selected from the groupconsisting of hydrogen (H) atoms, heteroatom-containing functionalgroups, alkyl groups, heteroatom-containing alkyl groups, cyclic groups,heteroatom-containing cyclic groups, aromatic groups,heteroatom-containing aromatic groups, and combinations thereof.
 14. Thesystem of claim 11, wherein at least one polishing additive is selectedfrom the group consisting of aminoethylethanolamine, polyethyleneimine,and a mixture thereof.
 15. The system of claim 12, wherein at least onepolishing additive is ethylenediamine.
 16. The system of claim 13,wherein at least one oxidizing agent is a peroxide, and wherein thesystem further comprises at least one passivation film forming agentcomprising one or more 5-6 member heterocyclic nitrogen-containingrings.
 17. The system of claim 3, wherein at least one polishingadditive is both (a) a compound selected from the group consisting ofpyrophosphates, condensed phosphates, phosphonic acids and saltsthereof, and (b) a compound selected from the group consisting ofamines, amino alcohols, amides, imines, imino acids, nitriles, andnitros.
 18. The system of claim 3, wherein at least one polishingadditive is both (a) a compound selected from the group consisting ofamines, amino alcohols, amides, imines, imino acids, nitriles, andnitros, and (b) a compound selected from the group consisting of thiols,thioesters, and thioethers, carbothiolic acids, carbothionic acids,thiocarboxylic acids, and thiosalicylic acids.
 19. The system of claim17, wherein at least one polishing additive is selected from the groupconsisting of 2-aminoethyl phosphonic acid, amino(trimethylenephosphonicacid), diethylenetriaminepenta(methylenephosphonic acid),hexamethylenediaminetetra(methylene phosphonic acid), and mixturesthereof.
 20. The system of claim 3, wherein the system further comprisesa source of ammonia.
 21. The system of claim 20, wherein the systemcomprises (i) aminotri-(methylenephosphonic acid) and (ii) ammonia or anammonium salt.
 22. The system of claim 3, wherein the system furthercomprises at least one stopping compound.
 23. The system of claim 3,wherein the system further comprises at least one polymeric compoundthat reduces the polishing rate of at least one layer associated withthe substrate.
 24. The system of claim 3, wherein the system furthercomprises at least one passivation film-forming agent.
 25. The system ofclaim 3, wherein the abrasive is a metal oxide abrasive.
 26. The systemof claim 25, wherein the abrasive is selected from the group consistingof alumina, ceria, germania, silica, titania, zirconia, and coformedproducts thereof, and mixtures thereof.
 27. The system of claim 26,wherein the abrasive is alumina.
 28. A method of polishing a substratecomprising contacting a surface of a substrate with the system of claim3 and polishing at least a portion of the substrate therewith.
 29. Amethod of polishing a substrate comprising contacting a surface of asubstrate with the system of claim 22 and polishing at least a portionof the substrate therewith.
 30. A method for polishing one or morelayers of a multi-layer substrate that includes a first metal layer anda second layer comprising the steps of: (a) contacting the first metallayer with the system of claim 3, and (b) polishing the first metallayer with the system until at least a portion of the first metal layeris removed from the substrate.
 31. A method for polishing one or morelayers of a multi-layer substrate that includes a first metal layer anda second layer comprising the steps of: (a) contacting the first metallayer with the system of claim 22, and (b) polishing the first metallayer with the system until at least a portion of the first metal layeris removed from the substrate.